Radiographic images of anatomical regions are a routine and valuable diagnostic and research tool. Such images are typically produced by placing a receiver behind or beneath a portion of a patient and exposing the patient to radiation such as X-rays, alpha rays, beta rays, gamma rays, ultraviolet rays, and the like. The receiver may be a direct radiography (DR) receiver that forms an image directly from the received radiation or, with conventional film or Computed Radiograph (CR) systems, a plate having a surface composed of excitable phosphors. As the radiation energy strikes the surface of the plate, a portion of the energy is stored by the phosphor-containing surface. Upon subsequent stimulation by visible light or other stimuli, the phosphor gives off light in direct proportion to the amount of radiation energy stored therein. Areas of the plate receiving unattenuated radiation absorb the most energy and thus produce the most light when subsequently stimulated. Areas in which lesser amounts of radiation energy are absorbed, due to the presence of the object (for example, a body region), produce a proportionately lesser amount of light when subsequently stimulated.
The image obtained from the receiver can be displayed for viewing. For example, the stored energy of the film can be photoelectrically detected and converted into a signal which is then further processed or used to reproduce the image on a photographic film, display CRT, or similar display device.
One common radiographic image utilized in clinical settings today is an image of the thoracic area of human body (for example, a standard chest x-ray). Such images provide useful information and are used to diagnose maladies ranging from lung and breast cancer to emphysema.
Before the radiographic image is reviewed/interpreted, the completeness of radiographic anatomy is typically checked. Missing or clipped portions of the radiographic anatomy can make it difficult or impossible to properly interpret the radiograph. For example, in a standard chest anterior-posterior view radiograph, complete imaging of both left and right lung regions is important for chest radiograph interpretation. If there were a cut-off or clipped region in the lung area, as shown in either of FIG. 1A or 1B, the radiograph would be rejected. FIG. 1A shows a chest x-ray image 10 that is clipped in the upper or apex region, as indicated by the dashed line box labeled C1. FIG. 1B shows a chest x-ray image 10 that is clipped at the side, as indicated by the dashed line box labeled C2.
If clipped anatomy prevents diagnosis, the x-ray image can be retaken. However, retaking the radiographic image is undesirable, since it exposes the patient to additional radiation. Rescheduling complications and delays, increased cost, and other administrative problems can also be among the unwelcome results of clipped anatomy. It would be advantageous, therefore, to detect clipped anatomy at the time that the radiograph is generated. On-the-spot detection of this type of problem can help to prevent unwanted delays due to patient re-scheduling and help to facilitate hospital workflow.
Thus, there is a need for a method and apparatus that allow an anatomy image-clipping problem to be automatically detected in a radiographic image that is obtained as digital data.